1. Field of the Invention
The present invention relates to a building material preferable for use as a wall material, roof material, floor material or the like, and to a method for producing the building material.
2. Description of the Related Art
Inorganic materials composed mainly of water-settable inorganic powder such as cement and wooden reinforcing materials such as wood pulp fiber have conventionally been used as building materials. Since these types of the inorganic materials have superior bending strength and other physical properties, they are used as the building materials such as residential interior wall materials, external wall materials, roof materials or floor materials after being coated.
When a plurality of these building materials are combined to form walls, roofs and floors, gaps may be formed between these building materials, allowing rainwater to enter the gaps and reach the back side of the building materials. Therefore, shiplap portions are formed on the each ends of these building materials, and the entry of rainwater to the back sides of these building materials is prevented by joining these shiplap portions. However, since this alone is unable to prevent the entry of rainwater enough, a bead-like waterproof portion referred to as a caulking is formed on the shiplap portion.
For example, Japanese Patent Application Laid-open No. H11-30017 discloses a building board having a female shiplap portion and male shiplap portion formed on the periphery thereof, wherein a caulking is formed by depositing a caulking material on the male shiplap portion and female shiplap portion to enable the caulking to prevent the entry of rainwater to the back side.